Target tracking technology is used for auto-focus, auto white balance and auto-exposure to shoot desired images and videos via camera devices. However, referring to FIG. 1A, conventional target tracking methods in which a tracking output rectangle 102, (namely, a tracking output area or a tracking output block) is fitted to the size and the shape of a tracked target A are likely to wrongly track a similar or the same target obstacle B especially when the tracked target A and the obstacle Bare partially overlapped, that is, when both the tracked target A and the obstacle B appear in the tracking output rectangle. For example, if the target tracking technology is used in an auto-focus function, wrong tracking results may cause blurred images shot because focused regions in the shot images may be wrong obstacles.
Other methods have the same output data format as the conventional target tracking methods. Output information of most conventional target tracking methods is a rectangle which is fitted to the size and the shape of a tracked target. But for the auto-focus function of a camera, this rectangle may cause a low auto-focus accuracy problem. Because the rectangle information contains background areas, an auto-focus module may sometimes focus on a background area inside the tracking output rectangle. For example, referring to FIG. 2A, the input image at the left side is converted, and an image at the right side is outputted. As the tracking output rectangle of the output image comprises a plurality of background areas (for example, five background areas shown in FIG. 2A), the camera may sometimes focus on the background area inside the tracking output rectangle during auto-focus.